Electronic image evaluating device and evaluation method

ABSTRACT

An electronic image evaluating device includes at least one area sensor that is provided with a plurality of photosensitive pixels. Each of these pixels will emit an electric output signal in response to the light input signal that it receives. The intensity of the electric output signal correlates with the light input signal. This electric output signal is evaluated in an evaluation unit as image information. The pixels of the area sensor can be controlled and evaluated individually, or in groups. Any sector of the maximum monitorable scanning area can be selectively evaluated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is the U.S. National Phase under 35 USC 371 ofPCT/DE 03/00569, filed Feb. 22, 2003; published as WO 03/073084 A1 onSep. 4, 2003 and claiming priority to DE 102 08 286.3, filed Feb. 26,2002, the disclosures of which are expressly incorporated herein byreference.

FIELD OF THE INVENTION

The present invention is directed to a method for using an electronicimage evaluating device. The device has at least one area sensor with aplurality of light-sensitive pixels. The pixels can be triggerable andevaluated individually or in groups.

BACKGROUND OF THE INVENTION

Electronic image evaluating devices for checking printed products areknown, with which evaluating devices defined features of a printedproduct can be recorded and evaluated. Normally, individually adaptedsensors or cameras are used for checking these special features. Sincethe position of these features, or the number of features to beevaluated can be basically arbitrary, the number and positioning of theappropriate sensors or cameras of the image evaluating device must beadapted correspondingly. Therefore, when using such camera or sensorsystems adapted to individual features, it is necessary for theindividual sensors or cameras to be adjustably situated so that they canbe positionable above various positions of the features to be evaluated.

Measuring or dependable assessment of the features to be evaluatedrequires a fixed scale of both image dimensions. The fixed scale canonly be assured by recording an image by the use of area image sensors,because the image sensor area itself constitutes this spatialinterrelation of the imaged objects with respect to each other. In linecamera systems, the spatial interrelation of the imaged objects is notassured with the required dependability because of the chronologicalsynchronization of the image lines, which cannot always be maintained.

U.S. 2002/0018600 A1 describes an image scanner, whose sensor field isselectively read out.

DE 41 36 461 C2 discloses a device for inspecting large areas of printedproducts. This device uses several parallel operated area sensors.

WO 00/42381 A1 describes an image evaluating device with an area sensorhaving a plurality of light-sensitive pixels. The pixels can beindividually evaluated, so that freeely selectable segments can beselectively evaluated.

EP 809 395 A2 discloses a method for operating an area sensor. Eachpixel can be selected and can be evaluated individually or in groups.

SUMMARY OF THE INVENTION

The object of the present invention is directed to providing anelectronic image evaluating device and to providing a method forevaluation.

In accordance with the invention, the object is attained by providing anelectronic image evaluating device having at least one area sensorhaving a plurality of light-sensitive pixels. Each such pixel emits anelectrical output signal as a function of the light input signal itreceives. The strength of the electrical output signal can be evaluatedin an evaluation unit as image information. The pixels of the areasensor can be triggerable and evaluated individually or in groups.Freely selectable segments of the maximally observable scanning area canbe selectively evaluated. The image to be evaluated may be a printedproduct that is conveyed past the area sensor. The segments selected bythe individual area sensors may be selected at a function of theconveying movement. A flash device may be provided for illuminating theimage. A reference marker can be applied to the image.

The invention is based on the basic concept of employing area sensorsfor the electronic image evaluating device, with the area sensors havingpixels that can be selected and evaluated individually and/or in groups.Such freely addressable area sensors permit the choosing of freelyselectable segments from the maximally observable scanning area of thearea sensor, which observable scanning area results from the size of thearea sensor and the optical device appropriately arranged in front ofit. Only the image data from these selected segments is passed on to adownstream-located electronic evaluation device, so that the selectedimage data can be evaluated there. The remaining segments of the maximumscanning area are blanked out and are not taken into account in theelectronic evaluation device. As a result, it is possible to select theimage data to be evaluated, depending on the application, by the use ofan appropriate triggering of the area sensor. Thus, the features to beevaluated can be recorded at any arbitrary position on the printedproduct without a mechanical displacement or an adjustment of theindividual sensors being necessary.

Furthermore, the pixels of at least one area sensor, for example a CMOSor complementary metal oxide silicon sensor, can also be read out onlypartially. Individual image areas can thus be selectively blanked out inorder to reduce the amount of image data to be processed. From thesedata, it is possible to determine the position of a segment, as well asto obtain image data of a segment with reduced resolution.

These CMOS sensors have an image structure corresponding to a memorymodule, so that individual pixels can be interrogated like memory cells.Thus, only image elements which are actually intended to be evaluatedneed to be read out.

To be able to increase the scanning area which can maximally be observedby the image evaluating device, without having to employ correspondinglylarger and larger area sensors, it is possible to provide several areasensors in the image evaluating device. The image data from the severalindividual area sensors are evaluated together in the downstream locatedevaluating device. As a result, it is possible to achieve, by thecombination of several area sensors, the evaluation of a very largemaximally observable scanning area with the image evaluating device byusing relatively inexpensive standard components.

So that, when employing several individual area sensors, no areas areformed which cannot be evaluated, the maximally observable scanningareas of the several individual area sensors should overlap at leastslightly. The image data emanating from the overlapping areas can thenbe taken into consideration in the downstream-located image evaluatingdevice in such a way that any such overlapping area is evaluated onlyonce.

In order to be able to evaluate a printed product with greateffectiveness, by utilization of the image evaluating device, aconveying arrangement should be provided in the image evaluating device,by the use of which conveying arrangement the printed product can beconveyed past the area sensor. In this connection, it is particularlyadvantageous if the pixels of the several individual area sensors can beselected and evaluated as a function of the conveying movement of theprinted product. As a result, it can be achieved that the segmentsselected for observation by the several individual area sensors areselected as a function of the conveying movement of the printed product.

Sufficient illumination of the printed product is often required fordependable image evaluation. An illumination arrangement, in particulara flash illumination arrangement, should therefore be provided in theimage evaluating device.

As an alternative to flash illumination, it is also possible to employ aconstant light illumination, if an electronic full image shutter isprovided.

The full image shutter limits the chronological integration of the lightin the image sensor in an electronic way.

Electronic image evaluating devices are often used for electronicallyevaluating webs of printed material, which webs have been repeatedlyimprinted with a recurring pattern. With such evaluation tasks, it isparticularly advantageous if a reference marker is assigned to eachindividual pattern on the web of imprinted material. In this case, asensor arrangement, by the use of which the reference markers can bedetected, should be provided in the electronic image evaluating device.With this sensor arrangement, it is possible for the sensor device toemit a synchronizing signal, by the use of which synchronizing signalthe image evaluating device can be synchronized with the movement of theweb of imprinted material.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention are represented in thedrawings and will be described in greater detail in what follows.

Shown are in:

FIG. 1, a schematic depiction of the structure of an image evaluatingdevice in accordance with the present invention, and in

FIG. 2, a perspective plan view of a printed product to be evaluatedwith various features to be evaluated.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, there may be seen an image evaluatingdevice, generally at 01, in accordance with the present invention. Inthe image evaluating device 01, which is schematically represented inFIG. 1, a web 02 of imprinted material can be conveyed underneath anarea sensor system with four individual area sensors 03, 04, 06 and 07.These individual area sensors 03, 04, 06, and 07 are arranged on acommon support element. An optical unit 08 is assigned to each of theindividual area sensors 03 to 07, by the use of which optical units 08 adefined image area of the web 02 of imprinted material is produced onthe light-sensitive pixels of the several individual area sensors 03 to07.

Maximally observable scanning areas 09, 11, 12 and 13 are a result ofthe type of area sensors 03 to 07 used, the properties of the opticalunits 08 used with the area sensors and the distance between the opticalunits 08 and the web 02 of imprinted material, which web 02 of imprintedmaterial can be evaluated by the use of the area sensors 03 to 07. Eachof the maximally observable scanning areas 09 to 13 is approximatelyrectangular. Adjoining scanning areas 09, 11, 12 and 13 overlap inoverlap areas 14, 16 and 17 respectively. As a result, it is possible,by the combination of the area sensors 03 to 07 to evaluate a totalscanning area, which is rectangular as a whole, and whose width isslightly greater than a width of the web 02 of imprinted material to beevaluated.

The web 02 of imprinted material to be evaluated is represented inprinted form in FIG. 2. Representative image patterns 18 and 19 havebeen imprinted on the web 02 of imprinted material in repeated patterns.Furthermore, a reference marker 23 which is assigned to each imagepattern, has been imprinted on the web 02 of imprinted material. Forevaluating the result of printing on the web 02 of imprinted material,it is now intended to selectively evaluate respective rectangularsegments 21 and 22 of the printed image in the area of the imagepatterns 18 and 19, and to compare these evaluated rectangular segments21 and 22 of the printed image patterns 18 and 19 with reference data.

The reference marker 23 can also represent a detection area which couldbe judged, for example in regard to the positions of the color fieldswith respect to each other; i.e. for register measuring. The referencemarker 23 can also be used for pattern reference.

The detection of the reference marker 23 does not necessarily have to beperformed with the multi-area sensor system itself. An additional sensorcan also be provided, which is only logically assigned to the system.Moreover, synchronization with the pattern could also be derived from amachine signal.

The web 02 of imprinted material to be evaluated is conveyed underneaththe several individual area sensors 03 to 07. As soon as the referencemarker 23 has been detected, an appropriate synchronization signal isgenerated, so that thereafter first the image pattern segment 21, andsubsequently the image pattern segment 22 can be recorded, positionallycorrect, by use of the several individual image sensors 03 to 07 andthese segments 21 and 22 can be evaluated. In the course of thisevaluation, only the pixels of the individual area sensors 03 and 07 aretriggered, so that only the segments 21 and 22 are recorded. Theremaining areas of the web 02 of imprinted material which are passedunderneath the image sensors 03 to 07 are blanked out and are notrecorded or evaluated.

While a preferred embodiment of a method for using an electronic imageevaluating device, in accordance with the present invention, has beenset forth fully and completely hereinabove, it will be apparent to oneof skill in the art that various changes in, for example the structureof the web conveying assembly, the number of individual area sensorsutilized and the like could be made without departing from the truespirit and scope of the present invention which is accordingly to belimited only by the following claims.

1-23. (canceled)
 24. A method for evaluating an image including:providing an electronic image evaluating device; providing at least onearea sensor, having a maximally observable scanning area, in saidelectronic image evaluating device; providing a plurality oflight-sensitive pixels in said at least one area sensor, each of saidpixels emitting an electrical output signal as a function of a lightinput signal received by each said pixel; correlating a strength of eachsaid electrical output signal with said light input signal received byeach said pixel; providing an evaluation unit; using said evaluationunit for evaluating said electrical output signals as image information;triggering said pixels in each said at least one area sensor selectingindividually and as a group; evaluating freely selectable signals ofsaid maximally observable scanning area; providing said image as aprinted product; providing a conveying arrangement in said electronicimage evaluating device; using said conveying arrangement for conveyingsaid printed product past said at least one area sensor; and selectingsaid signals of said maximally observable scanning area of said at leastone area sensor as a function of a conveying movement of said printedproduct.
 25. The method of claim 24 further including providing aplurality of said area sensors in said electronic image evaluatingdevice.
 26. The method of claim 24 further including providing anillumination device for said electronic image evaluating device.
 27. Themethod of claim 26 further including providing said illumination deviceas a flash device generating flashes at a defined repeat frequency. 28.The method of claim 26 further including providing said illuminationdevice as a full image shutter.
 29. A method for evaluating an imageincluding: providing an electronic image evaluating device; providing atleast one area sensor, having a maximally observable scanning area, insaid electronic image evaluating device; providing a plurality oflight-sensitive pixels in said at least one area sensor, each of saidpixels emitting an electrical output signal as a function of a lightinput signal received by each said pixel; correlating a strength of eachsaid electrical output signal with said light input signal received byeach said pixel; providing an evaluation unit; using said evaluationunit for evaluating said electrical output signals as image information;triggering said pixels in each said at least one area sensor selectingindividually and as a group; evaluating freely selectable signals ofsaid maximally observable scanning area; providing said image as aprinted product; providing said printed product as a web of imprintedmaterial imprinted with a repeating patter; assigning a reference markerto each said pattern; providing means for moving said web of materialpast said electronic image evaluating device; and synchronizing said webmovement past said electronic image evaluating device using saidreference marker.
 30. The method of claim 24 further including providingsaid maximally observable scanning area as a rectangle.
 31. The methodof claim 25 further including providing said maximally observablescanning area of each said area sensor as a rectangle.
 32. The method ofclaim 25 further including providing said plurality of said area sensorshaving overlap areas of said maximally observable scanning areas. 33.The method of claim 25 further providing providing said maximallyobservable scanning areas of said plurality of area sensors as arectangular total scanning area.
 34. The method of claim 25 furtherincluding providing a support element and arranging said plurality ofsaid area sensors on said support element.
 35. The method of claim 24further including providing an illumination arrangement in saidelectronic image evaluating device.
 36. The method of claim 29 furtherincluding providing an illumination arrangement in said electronic imageevaluating device.
 37. The method of claim 35 further includingproviding said illumination arrangement as a flash illumination device.38. The method of claim 36 further including providing said illuminationarrangement as a flash illumination device.
 39. The method of claim 37further including providing said flash illumination device being capableof generating flashes at a defined repeating frequency.
 40. The methodof claim 38 further including providing said flash illumination devicebeing capable of generating flashes at a defined repeating frequency.41. The method of claim 24 further including providing a full imageshutter in said electronic image evaluating device.
 42. The method ofclaim 29 further including providing a full image shutter in saidelectronic image evaluating device.
 43. The method of claim 24 furtherincluding using said electronic image evaluating device for checking aweb having said printed product arranged as a repeating pattern andproviding a reference marker assigned to each said pattern.
 44. Themethod of claim 29 further including providing a sensor forsynchronizing said electronic image evaluating device with movement ofsaid web.
 45. The method of claim 43 further including providing asensor for synchronizing said electronic image evaluating device withmovement of said web.
 46. The method of claim 44 further includingproviding said sensor in said electronic image evaluating device. 47.The method of claim 45 further including providing said sensor in saidelectronic image evaluating device.
 48. The method of claim 44 includingproviding said sensor separate from said electronic image device. 49.The method of claim 45 including providing said sensor separate fromsaid electronic image device.
 50. The method of claim 24 furtherincluding providing an optical device for said at least one area sensor.51. The method of claim 29 further including providing an optical devicefor said at least one area sensor.
 52. The method of claim 24 furtherincluding providing said at least one area sensor as a CMOS sensor. 53.The method of claim 29 further including providing said at least onearea sensor as a CMOS sensor.